Physics Questions: Thermodynamics, Newton and Kepler Laws, and planetary motion - Thanks for any help!?

water trampoline orbit image

Carter07

7) On an extremely hot day you fill a 12 oz cup half full of (00C) ice and then fill the cup with water which is at room temperature. The water cools down by:
A) Transfer of thermal energy from the ice to the water.
B) Transfer of thermal energy from the water to the ice.
C) The ice melts by absorbing thermal energy from the outside air which cools the water.

8) You are twirling a ball tied to the end of a string around your head. If the string breaks while the ball is directly to your right and moving forward, the ball will go:
A) To the right.
B) Straight ahead.
C) Spiral outward.
D) Spiral inward.

I KNOW THE BALL WILL CONTINUE IN THE SAME DIRECTION I JUST DON'T KNOW WHICH OF THESE OPTIONS DESCRIBES THAT.


9) Keplerâs law T2/a3 works for:
A) The orbits of the earth and the moon
B) The orbits of Mars and a geosynchronous satellite
C) The orbits of Saturn and Titan (a moon of Saturn)
D) The orbits of Venus and Mars.


10) A gymnast bounces upward from a trampoline, then falls back. During the time she is
airborne,
A) her velocity is a constant on the way up, and the way down. Only the direction
of the velocity changes.
B) her velocity changes, and there is no acceleration.
C) both her velocity and her acceleration changes from up to down.
D) her velocity changes and her acceleration is downward

11. You are trying to sleep in an unheated cabin in northern Alaska and everything around you is terribly cold. You can't find a blanket anywhere in the cabin, but you find several rolls of : (a) thick, low-density black paper, and (b) aluminum foil. To keep warmest, what order should you put them in?
A) aluminum foil on the inside, thick black paper on the outside. THIS IS WHAT I THINK
B) thick black paper on the inside, aluminum foil on the outside.
C) aluminum foil only.
D) thin black paper only.


12) You are playing hockey with friends on a very large frozen pond. The hockey puck is at your feet motionless. You take a slap-shot with your hockey stick and the hockey puck goes zooming off at a high rate of speed sliding along the ice. The hockey puck eventually comes to a stop because
A) there is no net forward force on the puck and so it will eventually slow down.
B) friction between the puck and the ice will do enough negative work on the puck to
equal the positive work done by you on the puck.
C) friction between the puck and the ice will do more negative work on the puck than
you did positive work on the puck.
D) friction between the puck and the ice will do less negative work on the puck than you did positive work on the puck.

13) On a cold winter day, you open the bathroom door and step inside. Everything in the room has the same temperature, but the floor tiles feel much colder than the towels hanging inside the room. If you drop one of these towels on the floor, heat will
A) flow from the tiles to the towel for a while and then stop, which makes the towel feel warmer to stand on.
B) flow from the towel to the tiles.
C) flow from the tiles to the towel.
D) not flow between the towel and tiles

Answer
7. B) Transfer of thermal energy from the water to the ice.
8. B) Straight ahead. (many people think the answer is "to the right")
9. Technically, Kepler's third works for all of these, but the only "pair" is D.
10. D) her velocity changes and her acceleration is downward
11. I'd go with B, but you could be right
12. B) friction between the puck and the ice will do enough negative work on the puck to
equal the positive work done by you on the puck.
13. D) not flow between the towel and tiles. (After all, they're the same temperature. The tiles just FEEL colder.)

What makes the planets orbit and not fall in?

Jon Jon

Bare with me:
The sun, for example, is like a bowling bowl sitting on a trampoline. If I place a tennis ball on the tramp somwhere around the bowling ball, the tennis ball will fall immediately to the bowling ball. If I was in a vacuum and did this, I assume, I'd get the same result. If, on the other hand, I rolled the tennis ball around the curve of the trampoline it would (ideally) spin around a few times a fall in closer and closer each time like water in a drain. In a vacuum, though, it creates centrifugal force as it spins and this perfect balance of gravity and centrifugal force keeps the tennis ball (earth) from falling into the sun (bowling ball). Is this all correct so far?
But, what, in space, made the planets begin their orbit of the sun? What I mean is, when the solar system was created it was created by a constant orbit of particles around the sun. But what made them orbit rather than just fall into the sun? Because there was no outside force to start the orbit (like me throwing the tennis ball).

In summary, how is the earth orbiting the sun right now instead of just falling, in a straight line, directly into the sun, immediately, when it was just a bunch of dust in space?

Answer
Well I haven't found a definite answer but have thought about this many times before and have hit upon an empirical which goes as follows.

They say that the Sun was originally a fast spinning ball of fire. It is possible that the planets were lumps that were thrown out of the Sun as molten lumps of lava at that time. these lumps would obviously have been thrown out in a tangential direction (to the surface of the Sun). they would have travelled outwards in that direction. The force of gravity of the Sun would have caused deceleration till a point of equilibrium would have been reached between the motion of the lump (planet) and the gravitational pull of the Sun, thus resulting in the linear motion of the planets turning into orbital motion around the Sun.

This is analogous to the stone at the end of a string being given a tangential thrust to set it revolving about an axis (the fixed end of the thread).



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